Straightening machine



Sept. 20, 1966 c, POHLER ETAL 3,273,364

STRAIGHTENING MACHINE Filed Oct. 26, 1964 5 Sheets-Sheet 1 NVENTOR 5 at; L yaw/o POI/L A? 21/00! F JIFEU -e BY p 'auuJ J ATTORNEY Sept. 20, 1966 c. PQHLER ETAL 3,273,364

STRAIGHTENING MACHINE 5 Sheets-Sheet 2 Filed Oct. 26, 1964 noun H'Hno ATTORN EY Sept. 20, 1966 c, POHLER ETAL 3,273,364

STRAIGHTENING MACHINE Filed 001;. 26, 1964 5 Sheets-Sheet 5 ATTORNEY United States Patent 3,273,364 STRAIGHTENENG MACHINE Carl Ludwig Pohler, Solingen, and Rudolf Breuer, Solingen-()hligs, Germany, assignors to Th. Kieserling & Albrecht Werkzeug-maschinenfabrik, Solingen, Rhineland, Germany Filed Oct. 26, 1964, Ser. No. 406,436 Claims priority, application Germany, Get. 24, 1963, K 51,169 14 Claims. (Cl. 72-12) The present invention relates to machines for straightening tubes, bars, rods and similar elongated workpieces. More particularly, the invention relates to a machine which is especially suited for straightening solid or hollow workpieces of circular or other cross section in a continuous operation.

The output of a modern rolling mill or of a modern apparatus for the production of seamless or welded tubes is very high. Nevertheless, the manufacturers strive to further increase the output of such apparatus which, in turn, means that all other machines which cooperate with a rolling mill or the like must also operate at a very high speed in order to process the workpieces at the same rate. For example, a rolling mill is normally followed by a straightening machine which will eliminate deformations and which insures that the stock advancing to storage or to further processing is free of up or down bow, of spiral twist or other deformations. In order to insure that the workpieces are fed into and removed from the straightening machine in a fully automatic way, such machines are equipped with a control unit whose elements regulate the operation of devices which feed or withdraw consecutive workpieces from the straightening station, of devices which advance the workpieces through the straightening station, of devices which brake a treated workpiece upon withdrawal from the straightening station, and/or of devices which cause the workpieces to move back and forth through the straightening station, i.e., which cause the straightening rolls to reverse the direction of rotation whenever the straightening operation must be carried out in two or more steps.

The elements of control units for tube or bar straightening machines normally comprise limit switches, photoelectric cells or magnets. Limit switches are not fully satisfactory when the straightening machine is to operate at a very high speed because the inertia of a limit switch prevents the machine from operating at a speed which corresponds to that of a modern rolling mill. Furthermore, and since the end portions of a workpiece which passes through the straightening machine often vibrate at a high frequency, such vibratory movements will cause the limit switches to open and close at rapidly following intervals with resultant wear and liklihood of malfunction. It is to be noted that a limit switch opens or closes in response to actual engagement with the workpiece.

A photoelectric control element is more satisfactory because its parts need not come in actual contact with the workpieces. However, such control elements are likely to be affected by dust and, in order to be sufiiciently sensitive over a comparatively wide range, they must consist of a battery of small cells each of which should have its own source of light. Small particles of dust may cause false operation and the control unit is rather expensive.

Control units which utilize magnets are satisfactory when the workpieces consist of ferrous material. However, when the workpieces consist of copper, brass, aluminum or other nonferrous material, a control unit utilizing permanent magnets or electromagnets is ineffective.

Accordingly, it is an important object of our invention to provide an improved straightening machine for tubular or bar stock whose control unit is constructed and assembled in such a way that it is equally effective in connection with ferrous and nonferrous materials, which can operate at any desired speed, and whose elements need not come in actual contact with the workpieces so that the wear on such elements is negligible.

Another object of our invention is to provide a control unit which is equally effective in connection with shorter or longer workpieces, with workpieces of different diameters, and which is not affected by eventual vibrations of a workpiece in the course of a straightenmg operation.

An additional object of the invention is to provide a straightening machine whose control unit will operate with unchanging accuracy regardless of the speed at which the workpieces are being advanced to, through, or away from the straightening station.

With the above objects in View, one feature of our invention resides in the provision of a straightening machine for bars, tubes and similar elongated workpieces which comprises a plurality of cooperating straightening rolls adapted to be driven at different speeds and in a clockwise or counterclockwise direction, a first conveyor for advancing untreated workpieces seriatim to the straightening station which accommodates the straightening rolls, a second conveyor for receiving treated workpieces from the straightening station, first transfer means operative to feed workpieces to the first conveyor, second transfer means operative to remove workpieces from the second conveyor, and novel control means for operating the first and second transfer means in a predetermined sequence. The control means comprises a pair of induction coils which are respectively disposed between the straightening station and the first and second conveyors. Each coil defines a passage for a workpiece respectively advancing toward and away from the straightening station to produce impulses which are utilized to operate the two transfer means. Such impulses are produced when a workpiece enters and/or leaves the respective coil and they may also be used to regulate the drive for the rolls of the first conveyor, to regulate the drive for the rolls of the second conveyor, to change the speed and/ or the direction of rotation of the straightening rolls, to reverse the direction of rotation of the rolls of the first and second conveyors, and to effect all such operations in a predetermined sequence.

The coils are not affected by dust and need not come in actual contact with the workpieces. Each of these coils is connected in a suitable electric circuit including amplifiers, resonant circuits, relays, time delay devices and solenoids which cooperate to insure that the straightcning machine will operate in a fully automatic way and that the sequence in which the various parts operate will be determined by the workpieces passing: through the one or the other induction coil.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved straightening machine itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a schematic top plan view of a straightening machine which is constructed in accordance with our invention;

FIG. 2 is a diagram showing a portion of the electric circuit for the control unit of the straightening machine;

FIG. 3 is an enlarged transverse vertical section as seen in the direction of arrows from the line III-III of FIG. 1 and illustrates a transfer element which serves to feed workpieces onto the first conveyor of the straightening machine;

FIG. 4 is another transverse vertical section as seen in the direction of arrows from the line IVIV of FIG. 1 and illustrates a pair of rolls which form part of the first conveyor and serve to advance workpieces into the straightening station; and

FIG. is a further transverse vertical section as seen in the direction of arrows from the line VV of FIG. 1 and shows one of a series of transfer elements which serve to remove finished workpieces from the second conveyor.

Referring to FIG. 1, there is shown a straightening machine 1 defining a straightening station ST which accommodates a series of straightening rolls 1a. The machine 1 further includes a first conveyor 2, called supply conveyor, whose rolls 6, 6a may advance untreated workpieces 4a to the station ST, and a second conveyor 3, called take-off conveyor, whose rolls 12 support a treated workpiece 4a.

The supply conveyor 2 is adjacent to one side of a magazine including a grate 5 which serves to accommodate a supply of untreated workpieces 4 shown by phantom lines. This grate includes transfer elements 5a (shown in FIG. 3) which deliver the workpieces 4 seriatim onto the rolls 6 (arrow 71)) so that the workpiece 4a. which has been transferred onto the supply conveyor 2 is in accurate alignment with the straightening rolls 1a at the station ST. The roll 6a is movable vertically and cooperates with the foremost roll 6 which is also movable vertically to advance the workpiece 4a into the station ST at Which the workpiece is engaged and treated by the rolls 1a in a manner known per se. The direction in which the workpiece 4a advances in response to descent of the roll 6a and simultaneous upward movement of the rolls 6 is indicated by an arrow 7.

Once the workpiece 4a has passed through the station ST and is about to move beyond the last set of rolls 1a, the control unit of the machine 1 causes a braking roll 11 to descend and to engage the trailing portion of the workpiece. The roll 11 then cooperates with the rearmost roll 12 to brake the workpiece 4a and to arrest it in the position 4a. This workpiece is then ready to be engaged by transfer elements 13a (see FIG. 5) of a second magazine including a grate 13 which is laterally adjacent to the take-off conveyor 3 and serves to store the finished workpieces some of which are shown by phantom lines at 4'. The arrow 7a indicates the direction in which the Workpieces are transferred from the take-off conveyor 3 onto the second grate 13.

Briefly stated, the control unit of the straightening machine 1 comprises two induction coils 8, 8a which are respectively provided between the station ST and the conveyors 2 and 3. The workpiece 4a will advance through the passage defined by the coil 8 while it moves toward the first set of straightening rolls 1a. to thereby initiate a series of operations including delayed transfer of a fresh workpiece onto the conveyor 2 and lifting of the roll 6a simultaneously with lowering of the rolls 6 so that the workpiece is then advanced solely by the rolls 1a of the machine 1. Thus, while advancing through the station ST, the workpiece will move at a speed which is determined by the variable-speed reversible motor 1b for the straightening rolls 1a.

When the leading end of the freshly treated workpiece enters the passage defined by the second coil 8a, it starts a series of operations including a delayed lowering of the braking roll 11 so that this roll will arrest the workpiece in the position 44'. Once the workpiece moves beyond the coil 8a, the latter sends an impulse which causes the roll 11a to move upwardly and which also causes the transfer elements 13a to move the workpiece from the conveyor 3 onto the grate 13.

When the machine 1 is used for straightening of bars and the nature of deformation of the stock is such that the straightening operation must be carried out in several consecutive steps or stages, the coils 8, 8a will send impulses which will cause the rolls 1, 1a, 6, 6a, 12 to reverse the direction of their rotation at predetermined intervals so that the workpiece will move back and forth prior to being discharged onto the conveyor 3 and grate 13.

The numerals 1c denote two tubular guides for the workpieces. The left-hand guide 1c introduces an untreated workpiece 4a into the elongated path defined by the rolls 1a, and the right-hand guide 1c will direct the treated portion of a workpiece into the passage defined by the coil 8a.

A portion of the electric circuit arrangement for the control unit of the straightening machine 1 is shown in FIG. 2. This circuit arrangement comprises a rectifier circuit 21 which is connected with a source 22 of A.-C. current and includes a stabilizer in the form of a transistor 23. The numeral 24 indicates a first resonant circuit which includes a transistor 25 and is connected with the output of the rectifier circuit 21. The current then flows through a first frequency amplifier including a transistor 26 and thereupon through a push-pull amplifier 27 which is connected to a second resonant circuit 29 whose coil 8 defines a passage for the workpiece 4a which advances to the straightening station ST. This workpiece destroys the equilibrium of the circuit 29 resulting in a volt-age drop across a resistor 30 to energize a relay 31 which is connected (as at 31a) in the circuit of the devices which regulate the operation of the transfer elements 5a and of the rolls 6, 6a. Also, and as mentioned above, the relay 31 may be connected in the circuit of the motor 1b for the straightening rolls 1a so that such rolls may be driven at a selected speed in a clockwise or counterclockwise direction whenever a workpiece is to be treated in two or more stages.

The circuit 24 must be tuned to the circuit 29, and this can be effected by a variable capacitor 29:: shown in FIG. 2. The instrument 32 indicates the exact resonance frequency of the circuit 29.

The other part of the circuit arrangement which includes the coil 8a is analogous to the one shown in FIG. 2 with the exception that the relay (corresponding to the relay 31) controls the operation of the transfer elements 13:: and rollers 11, 12.

FIG. 3 illustrates the manner in which the relay 31 may control the operation of transfer elements 5a which serve to transfer untreated workpieces from the grate 5 onto the supply conveyor 2. While FIG. 3 shows a single transfer element 5a, it is clear that the machine 1 may comprise two or more such transfer elements, especially if the workpieces 4 are long tubes or bars. For example, the grate 5 may be provided with as many as five transfer elements 5a, one for each inclined grate member or ramp 517 shown in FIG. 1. The transfer element 5a of FIG. 3 is pivotally secured to the grate member 512 by a horizontal shaft 40 and is reciprocable by the piston rod 41 of a double-acting hydraulic or pneumatic cylinder 42 attached to an upright column 50 of the grate 5. The conduits 43, 44 of the cylinder 42 lead to a solenoid valve 45 which is connected in circuit with the relay 31 and with a time delay 45a, see FIG. 2. The valve 45 will allow pressure fluid to flow through the conduit 44 in order to pivot the transfer element 5a in a counterclockwise direction in response to entry of a workpiece 4a into the coil 8. The foremost workpiece 4a (which has been transferred by the element 5a from the inclined surface 5b onto the inclined surface or platform 5b of the grate member 5a) rests against the end face of a pivotable cover member 46. The cover member 46 is pivotable at 47 and is attached to the piston rod 48 of a double-acting cylinder 4% which is connected with conduits 50, 51 leading to the solenoid valve 45. At the time the valve 45 receives an impulse to admit pressure fluid into the lower chamber of the cylinder 42 in order to pivot the element 5a to the broken-line position 5a, it also admits pressure medium through the conduit 49 to move the cover member 46 to the broken-line position 46'. The member 46 then allows the foremost workpiece 40 to enter a trough 52 which forms part of the supply conveyor 2 and is aligned with the path defined by the straightening rolls 1a. The relay 31 also sends an impulse to the device which lifts the roll 6a and lowers the rolls 6 so as to provide room for entry of the workpiece 4c into the conveyor 2.

The trough 52 may be used as a substitute for or in addition to the rolls 6. The manner in which the rolls 6, 6a are mounted and operated is shown in FIG. 4 which shows a single roll 6 mounted in a vertically reciprocable holder 55 connected to the piston rod 56 of a doubleacting cylinder 57. The cylinder 57 is connected with conduits 58, 59 leading to a solenoid valve 60 which is connected in circuit with the relay 31. The roll 6 is driven by .a shaft 61. The valve 60 is connected with an oil tank 60a by a supply conduit 6% which contains a pump 60c.

The roll 6a is mounted on a vertically reciprocable holder 62 which is connected with the piston rod 63 of a double-acting cylinder 64. This cylinder is connected with conduits 65, 66 leading to a solenoid valve 67 which is also connected in circuit with the relay 31. The roll 6a may but need not be driven because the roll 6 of FIG. 4 is driven by a reversible motor which rotates the shaft 61. The workpieces are admitted in the direction indicated by the arrow 7b and enter the trough 52 which is provided wth suitable cutouts to permit movement of rolls 6, 6a in engagement with the workpiece 4a. The axes of the rolls 6, 6a may but need not cross each other.

FIG. 5 shows one of the transfer elements 13a. This element is pivoted to an upright column 71 of the grate 13, as at 70, and is rockable by the piston rod 72 of a double-acting cylinder 73. There are several elements 13a, each connected to a separate column 71. The rolls 11, 12 of the conveyor 3 may be reciprocated in the same way as shown in FIG. 4 for the rolls 6, 6a. If reciprocable, all of the rolls 12 may be mounted on a common shaft which is movable up and down by a single cylinder or by two or more cylinders in synchronism with movement of workpieces through the straightening machine. As a rule, all of the rolls 12 will be driven and remain in their lower end positions to be out of the range of the leading end of the workpiece when the latter is treated and its leading end vibrates or oscillates in response to the action of rolls 1a.

The cylinder '73 of FIG. 5 is controlled by a solenoid valve (not shown) which is connected in circuit with the coil So.

When a workpiece 4a enters the passage defined by the coil, the valve 45 is energized through the delay device 45a to initiate the transfer of a fresh workpiece 4 from the grate 5. The valve 60 is also energized, together with the valve 67, to advance the workpiece 4a into the station ST when the trailing end of the preceding workpiece leaves the passage defined by the coil. The rolls 11, 12 will engage the trailing end of a freshly treated workpiece with 'a delay which is necessary to arrest the workpiece in optimum position for transfer onto the grate 13. Such transfer is initiated by the coil So when the trailing end of a freshly treated workpiece has passed therethrough.

The rolls 6, 6a are disengaged from the workpiece 4a .as soon as its leading end is engaged by the rolls 1a so that the workpiece then advances at the speed determined by the motor lb. The rolls 11, 12 will be disengaged from the workpiece 4a in response to an impulse produced by the coil 4:: when the trailing end of a workpiece has moved beyond this coil.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A straightening machine for bars, tubes and similar elongated workpieces, comprising a plurality of cooperating straightening rolls; a first conveyor for advancing untreated workpieces seriatim to said straightening rolls; a second conveyor for receiving treated workpieces from said straightening rolls; first transfer means operative to feed workpieces to said first conveyor; second transfer means operative to remove workpieces .from said second conveyor; and control means for operating said transfer means in a predetermined sequence, said control means comprising a pair of induction coils respectively disposed intermediate said rolls and said first and second conveyors, each of said coils defining a passage for a workpiece respectively advancing toward and away from said rolls to produce impulses which are utilized to operate said transfer means.

2. A machine as set forth in claim 1, wherein one of said conveyors comprises a pair of rolls one of which is movable toward the other roll to engage a workpiece therebetween, reciprocating means for moving said one roll with reference to the other roll, and an operative connection between said control means and said reciprocating means for actuating said reciprocating means in response to movement of a workpiece through one of said passages.

3. A straightening machine for bars, tubes and similar elongated workpieces, comprising a plurality of cooperating straightening rolls; a first conveyor for advancing untreated workpieces seriatim to said straightening rolls; a second conveyor for receiving treated workpieces from said straightening rolls, first transfer means operative to feed workpieces to said first conveyor; second transfer means operative to remove workpieces from said second conveyor; and control means for operating said transfer means in a predetermined sequence, said control means comprising resonant circuit means including a pair of induction coils respectively disposed intermediate said rolls and said first and second conveyors, each of said coils defining a passage for a workpiece respectively advancing toward and away from said rolls to produce impulses which are utilized to operate said transfer means.

4. A straightening machine as set forth in claim 3, wherein said first conveyor comprises a pair of cooperating rolls movable into and out of engagement with a workpiece on said first conveyor, means for rotating one of said last named rolls to advance the worpiece toward said straightening rolls and reciprocating means for moving said cooperating rolls with reference to each other, said control means comprising actuating means for operating said reciprocating means in response to passage of a workpiece through that coil which is adjacent to said first conveyor, said actuating means comprising time delay means for moving said cooperating rolls toward each other at the time said straightening rolls are free to begin the treatment of a fresh workpiece.

5. A straightening machine as set forth in claim 4, wherein said actuating means comprises means for moving said cooperating rolls away from each other on engagement of said straightening rolls with a fresh workpiece and further comprising motor means for driving said straightening rolls so that, once engaged by said straightening rolls, a workpiece advances toward said second conveyor at a speed determined solely by said motor means.

6. A straightening machine for bars, tubes and similar elongated workpieces, comprising a plurality of cooperating straightening rolls; a first conveyor for advancing untreated workpieces seriatim to said straightening rolls; a second conveyor for receiving treated workpieces from said straightening rolls; a first magazine adjacent to said first conveyor; a second magazine adjacent to said second conveyor; first transfer means operative to feed workpieces from said first magazine to said first conveyor; second transfer means operative to deliver treated workpieces from said second conveyor to said second magazine; and control means for operating said transfer means in a predetermined sequence, said control means comprising a pair of induction coils respectively disposed intermediate said rolls and said first and second conveyors, each of said coils defining a passage for a workpiece respectively advancing toward and away from said rolls to produce impulses which are utilized to operate said transfer means.

7. A straightening machine as set forth in claim 6, wherein each of said magazine comprises a grate which is laterally adjacent to the respective conveyor and wherein said conveyors are aligned with each other and with said straightening rolls.

8. A straightening machine as set forth in claim 7, wherein each of said transfer means comprises a plurality of transfer elements pivotally secured to the respective grates and double-acting fluid-operated cylinders arranged to pivot said transfer elements with reference to the associated grates, said control means comprising solenoid valves connected with said cylinders and energizable in response to passage of workpieces through said coils to thereby regulate the flow of a fluid medium to and from said cylinders.

9. A straightening machine for bars, tubes and similar elongated workpieces, comprising a plurality of cooperating straightening rolls defining an elongated path for the workpieces; guide means disposed at the opposite ends of said path; a first conveyor for advancing untreated workpieces seriatim to one of said guide means; a second conveyor for receiving treated workpieces from the other guide means; first transfer means operative to feed workpieces to said first conveyor; second transfer means operative to remove workpieces from said second conveyor; and control means for operating said transfer means in a predetermined sequence, said control means comprising resonant circuit means including a pair of induction coils respectively disposed intermediate said guide means and said first and second conveyors, each of said coils defining a passage for a workpiece respectively advancing toward and away from said rolls to produce impulses which are utilized to operate said transfer means.

10. A control unit for regulating the operation of movable parts in a straightening machine for elongated tubes, bars and similar workpieces, comprising resonant circuit means including a pair of axially spaced induction coils 8 defining passages for the workpieces and arranged to produce impulses in direct response to entry and removal of workpieces from such passages; and actuating means responsive to such impulses for operating said movable parts in a predetermined sequence.

11. In a machine for operating on bars, tubes and similar elongated workpieces, a work station; a first conveyor for advancing untreated workpieces seriatim to said work station; a second conveyor for receiving treated workpieces from said work station; first transfer means operative to feed workpieces to said first conveyor; second transfer means operative to remove workpieces from said second conveyor; and control means for operating said transfer means in a predetermined sequence; said control means comprising a pair of induction coils respectively disposed intermediate said work station and said first and said second conveyors, each of said coils defining a passage for a workpiece respectively advancing toward and away from said work station to produce impulses which are utilized to operate said transfer means.

12. In a machine for treating elongated workpieces such as bars, tubes and the like, tool means for treating the workpieces; first conveyor means for delivering untreated workpieces seriatim to said tool means; second conveying means for receiving treated workpieces from said tool means; and control means for controlling the operation of at least one of said means, said control means comprising resonant circuit means including an induction coil disposed intermediate said conveying means and defining a passage for a workpiece moving between said conveying means to produce impulses in response to movement of a workpiece, respectively, into and out of said passage, said impulses being utilized to control the operation rOf said one of said three first mentioned means.

13. In a machine according to claim 12, said induction coil being located intermediate said tool means and one of said conveying means, said resonant circuit means comprising a second induction coil disposed intermediate said tool means and the other of said conveying means and defining a passage for a workpiece moving between said other conveying means and said tool means to pnoduce impulses in response to the movement of a workpiece, respectively, into and out of said passage of said second induction coil which impulses are also utilized to control the operation of one of said three first mentioned means.

14. In a machine according to claim 12, wherein said control means is operatively connected to said first and second conveying means and said impulses are utilized to control the operation of said conveying means.

References Cited by the Examiner UNITED STATES PATENTS 3,148,563 9/1964 Harley et al. 72-14 CHARLES W. LANHAM, Primary Examiner.

R. D. GREFE, Assistant Examiner. 

1. A STRAIGHTENING MACHINE FOR BARS, TUBES AND SIMILAR ELONGATED WORKPIECES, COMPRISING A PLURALITY OF COOPERATING STRAIGHTENING ROLLS; A FIRST CONVEYOR FOR ADVANCING UNTREATED WORKPIECES SERIATIM TO SAID STRAIGHTENING ROLLS; A SECOND CONVEYOR FOR RECEIVING TREATED WORKPIECES FROM SAID STRAIGHTENING ROLLS; FIRST TRANSFER MEANS OPERATIVE TO FEED WORKPIECES TO SAID FIRST CONVEYOR; SECOND TRANSFER MEANS OPERATIVE TO REMOVE WORKPIECES FROM SAID SECOND CONVEYOR; AND CONTROL MEANS FOR OPERATING SAID TRANSFER MEANS IN A PREDETERMINED SEQUENCE, SAID CONTROL MEANS COMPRISING A PAIR OF INDUCTION COILS RESPECTIVELY DISPOSED INTERMEDIATE SAID ROLLS AND SAID FIRST AND SECOND CONVEYORS, EACH OF SAID COILS DEFINING A PASSAGE FOR A WORKPIECE RESPECTIVELY ADVANCING TOWARD AND AWAY FROM SAID ROLLS TO PRODUCE IMPULSES WHICH ARE UTILIZED TO OPERATE SAID TRANSFER MEANS. 